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Full text of "The manufacture and properties of iron and steel"

182
MBTALLUBGY OP IKON AND STEEL.
a high temperature. The union of the oxygen of the ore with the silicon and carbon sets free metallic iron, which is immediately dissolved by the bath.
. |r__ If the ore is added properly, it is reduced as fast as it is put in,
as will be evident from Table X-B, which shows the history of the metal and the slag in the groups above considered. In Group I an average of 1020 pounds of ore was used on each heat to decarburize, while on Group II only 850 pounds was added, but in spite of the addition of the ore the character of the slag remains unchanged.
/"There is an increase of FeO, but this does not show an increase in basicity, for the volume of slag is increasing, both from the wear of the hearth and the silica from the ore, so that in order that the composition of the slag should remain the same it would be necessary that there be a simultaneous supply of exactly the right proportions of both MnO and FeO. This cannot happen, for the metal after melting is nearly free from manganese, and since the ore contains none there is no source of supply of this element. With the dilution of the slag, there is a vacancy left for a base, and iron oxide is the only available candidate. That" this is the true explanation will be seen from the totals -of MnO and FeO, which show that the slag at the end of the operation is almost identical with the slag after melting, since the sum of these factors represents the real basicity of the cinder.
TABLE X-B. History of Metal and Slag in an Acid Furnace.
Subject.		Composition, per cent.			
		Group I. 19 heats soft coal gas.		Grout) II. 6 heats oil gas.	
		After melting	End of operation.	After melting.	End of operation.
Metal.	SI .................	.02 .09 .54	.02 .01 .18	.05 .06 .64	.01 .02 .12
	Mu .............				
	c ..............				
					
Slag.	SiO. ............ ;.	50.24 21.67 23.91 45.58	49.40 16.50 29.79 46.29	49.46 13.16 83 27 46.43	49.36 11.30 84.11 45.41
	MuO .............				
	FeO ............				
	MnO+FeO .......